Mixer for granular material



April 4, 1961 R. L. MCILVAINE MIXER FOR GRANULAR MATERIAL Filed Dec. 25,1957 [5 1%.5 INVENTOR.

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' R FOR GRANULAR MATERIAL The present invention relates to mixers andmore particularly to a new and improved means for evacuating mixers ofthe type employing rotatable mullers for mixing and mulling granularmaterial such as the core sand which is used in casting operations.

Mixers of the type with which the present invention is particularlysuited ordinarily employ a plurality of rotating mullers and plowsmounted in an open-topped crib or container into which large quantitiesof granular material to be'mulled' and mixed are placed. The plows areso designed as to cause mixing of the material as they travel throughit, any chunks of the material which may be present being broken up ormulled by the mullers. After the material has been satisfactorily mulledand mixed, it becomes necessary to remove the granular material from themixer, and a principal object of the present invention is to provide amixer employing a new and improved discharge means for enabling therapid and facile removal of the granular material from the crib.

Another object of the present invention is to provide a new and improveddischarge door and opening for use in a mixer.

A further object of the present invention is to provide a mixer of therotatable muller type employing a new I and improved discharge meanswhich makes use of the centrifugal force of the granular material in themixer for quickly and eificiently evacuating the material from themixer.

Another object of the present invention is to provide a new and improvedmuller construction employing a door and associated doorway partiallylocated in the bottom of the crib and partially located in a side wallof the crib, thereby to enable the rapid discharging of the granularmaterial from the crib.

Briefly, the above and further objects are realized in -accordance withthe present invention by providing a particularly shaped dischargeopening in the crib of a mixer of the type employing rotatable mullerand mixer elements. The mixer elements are designed to cause thematerial in the mixer to move toward and away from the center of thecrib into the paths of a plurality of muller wheels which roll alongcircular paths on the bottom of the crib. Therefore, in order to utilizethe natural movement of the material in the mixer to enhance theefiiciency of operation of the mixer during evacuation of the materialfrom the crib, the discharge opening is formed by adjacent openingsrespectively disposed in the side and in the bottom of the crib.Moreover, a single door is used to close this irregularly shapeddischarge opening during the mixing and mulling operation, and a novelseal is provided between the door and the crib to facilitate operationof the door.

Further objects and advantages and a better understanding of the presentinvention may be had from the following detailed description taken withreference to the accompanying drawings, in which:

Fig. 1 is a top plan view partially in section of a mixer embodying thepresent invention;

stem

Patented Apr. 4, 1961 Fig. 2 is a fragmentary sectional view taken alongthe line 2-2 of Fig. 1; and

Fig. 3 is a fragmentary perspective view of a portion of the mixer ofFig. I particularly showing the discharge opening and the associateddoor.

Referring now to the drawings and particularly to Fig. 1 thereof, thereis shown a mixer 1th comprising an opentopped cylindrically shaped crib11 formed of a hollow cylindrical Wall 12 which is suitably secured atthe bottom thereof to a circular bed plate 13. On the upper flat surfaceof the bed plate 13 is mounted a circular wear plate 14 which ispreferably constructed of hardened steel. As best shown in Figs. 2 and3, the bed plate has a depending flange 15 including an annular recessnear the top thereof in which the lower portion of the wall 12 isreceived. The mixer 10 is supported by four rectangularly arrangedpedestals 16 which have a substantially V-shape in. plan as seen inFig. 1. The upper ends of the pedestals 16 are secured, as by welding,to a plurality of plates '17 which are secured to the lower ends of theflange 15. The pedestals 16 thus support the crib 11 at a somewhatelevated position to provide space beneath the bed plate 13 for themounting of a motor (not shown) which drives the moving parts of themixer 10. The rotor of this drive motor is connected by means of asuitable drive shaft 18, which is vertically journaled at the center ofthe crib 11, to a cross head 19 on which a plurality of rocker arms 21and 22 are pivotally mounted. Suitable means, such, for example, as aspring (not shown) biases the rocker arms 21 and 22 toward the wearplate 14.

The granular material which may be placed in chunks into the crib 11 isbroken up by a pair of muller wheels 25 and 26 which are respectivelymounted in substantially diametrically opposed positions on a pair ofshafts 27 and 28 which are press fitted in holes in the rocker arms 21and 22. The principal longitudinal axes of the shafts 27 and 28 areperpendicular to the pivotal axes of the rocker arms 21 and 22 on thecross head 19. Each of the muller wheels 25 and 26 is rotatably mountedon its associated shaft 27, 28 on ball bearing assemblies suitablydisposed in the muller wheels 25 and 26 (not visible in the drawing)whereby rotation of the cross head 15! about the principal longitudinalaxis of the drive shaft 18 causes the muller wheels 25 and 26 to rollthrough the granular material. Since the wheels 25 and 26 are very heavyand are further biased toward the Wear plate 14, the granular materialis mashed or mulled between the wheels and the plate and any chunks ofthe material which may be present are broken up.

In order to thoroughly mix the granular material placed in the crib 11,a plurality of suitably shaped arcuate mixer elements or plow blades 31and 32 are mounted on the cross head 19, the blade 31 covering the outerportion of the crib 11 and the blade 32' covering the inner portion.Moreover, the blades 31 and 32 are so shaped that as the drive'shaft 18is rotated counterclockwise, as viewed in Fig. 1, the plow blade 31,which is disposed just inside the inner wall of the crib ll, causes thegranular material which is located in the outer portion of the crib tobe moved toward the center thereof, and the plow blade 32., which islocated near the center of the crib 11, causes the granular materialwhich is located near the middle of the crib to move toward theperiphery thereof. In the case of both plow blades, however, thetrailing edges of the blades 31 and 32 are in close proximity and justahead of a respective one of the muller wheels 25 and 26 so that as thegranular material is redirected by the plows 31 and 32 to cause mixingthereof itis also fed to the muller wheels to insure a good mullingaction. It will be apparent that while the granular material located inthe mixer 10 moves in both an inward and an outward direction, theoverall effect of the rotation of the muller wheels 25 and 26 and theplow blades 31 and 32 is to impart a circular, counterclockwise motion(Fig. 1) to the granular material which, due to the centrifugal forcewhich is thus exerted thereon, tends to move toward the periphery of thecrib 11.

After the granular material which has been placed in the mixer hasbeen'suificiently mulled and mixed, it becomes necessary to remove thegranular material from the mixer so that the material may be reused andin addition so that the mixer itself may be again used to mix and grindthe next batch of material. It will be apparent that in order to insurethe efficient operation of the mixer 10, the crib 11 should becompletely evacuated in as short a time as possible.

Therefore, in accordance with an important aspect of the presentinvention there is provided a discharge opening which is disposedpartially in the side and partially in the bottom of the crib 11. Inthis manner, as the granular material is pushed by centrifugal force andby the plow blade 32 toward the periphery of the mixer, it is forced outof the crib through the portion of the discharge opening which islocated in the side wall thereof. Although all of the material couldeventually be removed from the crib through an opening which wasdisposed only in the side wall thereof, because the plow blade 31 causesthe granular material to move toward the middle of the crib, theaddition of an opening in the bottom of the crib appreciably decreasesthe evacuation time of the mixer it It may be seen that in evacuatingthe chamber, the cross head is rotated and at first a large quantity ofthe material is forced out through the portion of the discharge openingin the side wall, but as the quantity of material in the crib diminishesbelow a certain quantity, most of the remaining material falls outthrough the portion of the opening in the bottom of the crib 11.

Considering in greater detail the discharge means of the presentinvention, there is provided in the side wall 12 of the crib 11 asomewhat rectangularly shaped opening 33 at a position adjacent to andaligned with a similar rectangularly shaped opening 36 in the plates 13and 14. As best shown in Fig. l, the portion 36 of the discharge openingextends toward the center of the crib 11 to a position just beyond theouter edge of the plow blade 32 so that the granular material which isdirected by the blade 32 toward the periphery of the crib 11 passesdirectly over the opening portion 36, thereby to increase the efficiencyof the evaucation operation. A generally L-shaped discharge door 38 ispivotally mounted on the wall 12 by means of a plurality of hinges 41secured to the wall 12 directly above the discharge opening 35.Consequently, the door 38 is pivotally movable to open and close thedischarge opening in the crib 11. The discharge door 38 has a fiat baseportion 39 and an upstanding arcuate wall portion 40 which cooperateswith the portion 39 when the door is in a closed position, shown in fulllines in Fig. 2, to cover both opening portions 35 and 36 of the overalldischarge opening and to uncover both of these openings when the door isin an open position as shown in dotted lines in Fig. 2.

in order to provide a seal between the door 38 and the portions of thecrib 11 which define the discharge opening, a pair of relatively narrowplates 44 are mounted on the upstanding arcuate portion 4% of the door38 and overhang the edges thereof. Since the material which must be heldin the crib 11 is of a coarse, granular nature, even though the door 38fits quite loosely in the discharge opening, the plates 44 provide asatisfactory seal along the upper sides of the door. A similar set ofplates 45 are provided along the side edges of the flat, bottom portionof the door 38. It will be apparent that the plates 44- and 45 inaddition to functioning as sealing members also act as stops tofacilitate closing of the door 33. Although the sets of plates &4 and4-5 satisfactorily seal the sides of the door 38 to the crib 11, asimilar plate, located along the leading edge 46 of the door 38, hasbeen found to be unsatisfactory since during the mixing operation someof the granular material becomes wedged between such a plate and theadjacent portion of the lower face of the bed plate 13. This thin layerof packed granular material remains on the bed plate 13 when the door 38is opened and interferes with the closing of the door 38 after the crib11 has been evacuated.

Therefore, in accordance with another feature of the present invention aseal is proved between the leading edge 46 of the door 38 and theadjacent portions of the bed and wear plates 13 and 14 by means of anarrow plate 51 secured to the bottom portion 39 of the door 38 throughthe medium of a spacer strip 52. Accordingly, the portion of the plate51 which extends over the bed plate 13 is spaced at a substantialdistance from it. Therefore, with the door 38 in a closed position, someof the granular material passes through the relatively large spacebetween the edge 36 of the door 39 and the portion of the dischargeopening through the plates 13 and 14 onto the shelf which is formed bythe plate 51. The material in the crib, being of a granular nature, doesnot continue to fiow out through this opening but builds up a cake ofcompressed material on the shelf as well as in the vertically disposedspace between the edge 46 of the door and the adjacent edge of thedischarge opening. Since the portion of the cake which is located on theplate 51 is quite thick, when the door 38 is opened to evacuate the crib11, all or at least most of this cake falls ofi so that when the door 38is again returned to a closed position only a small amount, if any, ofthe caked granular material is in a position to interfere with theclosing of the door. it has been found in using apparatus constructed inaccordance with the present invention that there is an insufficientamount of the cake remaining either on the plate 51 or on the bed plate13 to interfere with the proper closing of the door 38. By using thissealing arrangement, a simple locking means, such as a lever 53pivotally mounted by means of a pintle 54 secured to the bed plate 13,may be used for moving an integral locking member 55 beneath theadjacent plate 45 thereby to hold the door 38 in a closed position.

It will be understood that the present invention has been described inconnection with a manually operable door but that suitable hydraulic orpneumatic cylinders or any other suitable means may be used for openingand closing the door and, moreover, these devices can be controlled byan automatic timing circuit which opens the door after the mixer hasbeen operated for a predetermined time and closes it after apredetermined time has elapsed. In this manner automatic operation ofthe mixer 10 is effected. Also, where the door 38 is operated manually,its center of gravity is so disposed that when released it hangs in theposition shown in dotted lines in Fig. 2 so that the door 38 acts as adeflector during evacuation of the crib 11 to direct the granularmaterial below the lower portion 36 of the discharge opening so that asuitable truck or hopper placed thereunder may be used to collect thegranular material evacuated through the discharge opening.

While the invention has been described by means of a particularembodiment thereof, it will be understood that those skilled in the artmay make many changes and modifications without departing from the truespirit and scope of the invention, and accordingly, all such changes andmodifications which fall within the true spirit and scope of thisinvention are intended to be covered in the appended claims.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. In a mixer of the type employing rotatable mullers and mixingelements to mix material, a crib including vert al side walls and abottom wear plate secured periphery thereof to said side walls, meansdefining an opening in said wear plate adjacent to one of said walls,means defining an opening in said side wall at a position adjacent toand aligned with the opening in said wear plate, a discharge doorhingedly mounted on said crib above the opening in said side wall forpivotal movement on said crib, said door being substantially L-shaped incross section and including a base portion for reception in the openingin said wear plate and an upstanding portion for reception in theopening in said side wall, a plurality of narrow plates secured to theupright portion of said door and extending beyond the vertical sideedges thereof, another plurality of narrow plates secured to the bottomportion of said door and extending beyond the side edges thereof, and anarrow plate secured to said door and extending beyond the leading edgeof the bottom of said door, said last-mentioned plate being spaced asubstantial distance below the bottom of said door so that when saiddoor is in a closed position said plate overlaps a portion of said wearplate and is spaced a substantial distance therefrom.

2. A closure for a discharge opening in the side and bottom of a mixercrib, comprising an L-shaped door pivotally attached to the wall of saidcrib above said opening, said door being dimensioned for reception insaid opening, a plurality of narrow plates secured to the sides of theportion of said door receivable in the opening in the bottom of saidcrib, a narrow plate secured to said door and extending beyond theleading edge of the bottom of said door, said last-mentioned plate beingspaced a substantially greater distance below the bottom of said doorthan said plurality of narrow plates so that when said door is in aclosed position said plate overlaps a portion of said wear plate and isspaced a substantial distance therefrom, and a latch mounted on saidcrib and movable to a position behind said door to secure it in a closedposition.

3. In a mixer of the type employing rotatable mullers and mixingelements to mix material, a crib including vertical side walls and abottom wear plate secured throughout the periphery thereof to said sidewalls, means defining an opening in said wear plate adjacent to one ofsaid walls, means defining an opening in said wall at a positionadjacent to and aligned with the opening in said wear plate, a dischargedoor hingedly mounted on said cribe above the opening in said side wallfor pivotal movement on said crib, said door being substantiallyL-shaped in cross section and including a base portion for reception inthe opening in said wear plate and an upstanding portion for receptionin the opening in said side wall, and a plurality of narrow platessecured to said door and extending beyond the edges thereof.

References Cited in the file of this patent UNITED STATES PATENTS2,200,825 Hund May 14, 1940 2,303,319 Beardsley et al Dec. 1, 19422,377,307 Brown June 5, 1945 2,471,487 Granath May 31, 1949 2,603,381Bilek July 15, 1952 2,610,802 McIlvaine Sept. 16, 1952 2,652,174 SheaSept. 15, 1953

